Lactic acid bacteria and manganese-based additives for improved lucerne, perennial grass, and perennial grass-white clover preservation as silage

Abstract

Lactic acid bacteria (LAB) are commonly used as silage inoculants. Manganese sulphate (MnSO₄) has been proposed to protect certain LAB during oxygen exposure and improve silage aerobic stability (ASTA). The aim of the present study was to assess the efficacy of inoculants in preservation of different forages. A short-term screening trial investigated the effect of 24 additive treatments, compared to a negative control, on ensiling perennial grass in mini-silos (2.75 L) for 7 d. The additive treatments comprised different ratios of Lactiplantibacillus plantarum [IMI 507026, IMI 507027, and IMI 507028] and Pediococcus pentacaceus [IMI 507024 and IMI 507025], with or without MnSO₄. Target parameters, such as low levels of fresh matter loss, pH, acetic acid, ammonia-nitrogen fraction (NH₃–N/Total N), and high levels of lactic acid and ASTA, were considered for treatment selection. Eight treatments were selected based on a principal component analysis and hierarchical clustering of the target parameters. These selected treatments subsequently underwent a 100 d long-term trial using lucerne, perennial grass, and perennial grass-white clover forages. All silages treated with the eight additives exhibited an improved homolactic fermentation and a lower (p < .001) pH, acetic acid, and ethanol content than the control. Although DM losses and ASTA markedly improved in the treatments containing MnSO₄ in the short-term trial, these effects were not observed in the long-term trial. These outcomes suggest that the selected additives can improve silage fermentation quality across a broad range of forages, but further studies are required to assess the impact of MnSO₄ on ASTA.